The Whirlpool Galaxy (also known as Messier 51a,M51a, or NGC 5194) is an interactinggrand-designspiral galaxy located at a distance of approximately 23 million light-years in the constellationCanes Venatici. It is one of the most famous galaxies in the sky. The galaxy and its companion (NGC 5195) are easily observed by amateur astronomers, and the two galaxies may even be seen with binoculars.The Whirlpool Galaxy is also a popular target for professional astronomers, who study it to further understanding of galaxy structure(particularly structure associated with the spiral arms) and galaxy interactions.